SR4Wheel – How it all began

Let us go back to the Year 2014. New approaches and ideas were being developed at the Cologne University of Applied Sciences, Cologne, Germany in the faculty of Prof. Dr. Lohner, for a new research project in the field of electromobility.

Proceeding from the basis of the previous research project: ‘E4x4 – Research into E-drives with 4 independent E-engines’ together with the Cologne University of Applied Sciences‘ E-mobility project: ‘DrEM-Hybrid’, it became rapidly clear, that we could also realize other mutual mobility concepts by combining our gained knowledge and expertise.

The foundation for the ‘SR4Wheel’ was therefore already set, and the idea of converting and re-equipping a conventional existing E-series vehicle was born. The concept was to introduce a new form of ‘wheel hub and rim’ installed drive.

A switched reluctance machine

The employment of a switched reluctance machine as a drive unit directly activating the wheel hub, as well as within the interior construction of the wheel rim itself, has become the centerpiece of this research. Four electric motors – two at the front and two at the rear axle – will provide the required drive.

A switched reluctance machine is a design for an electric drive, where the torque of the rotor is generated solely by force of reluctance and not by Lorentz force. The drive unit therefore foregoes the use of expensive permanent magnets and the employment of rare and pricy ores, which production and acquisition are a liability to humans and nature.

The ‘SR4Wheel’ therefore relies on double sustainability in regards to environment protection – zero emissions by way of an efficient electric drive, as well as conservation of natural resources through an ‘intelligent’ use of components.

Where does the challenge lie and why is this concept not already in production?

Of course, electric drives for road vehicles have already been introduced and tested for decades, but not the switched reluctance machine. Among other reasons, this is due to the distinct vibration phenomenon of its drive, also known as Noise Vibration Harshness (NVH). This is the decisive negative factor preventing the adoption and production of this technology for wheel-hub driven propulsion ever since. Apart from the mechanical influence quantities involved, the complex interplay of 4 drive motors needs to be perfectioned and synchronized by means of sophisticated open-loop control electronics. This also involves the elaboration of new approaches for the development of control equipment, right through to realization via the necessary trials.

For this reason, the ‘SR4Wheel’ Research Team is taking up the challenge to seek out new solutions to drastically reduce the existing difficulties. We are confident in that we can master the introduced challenges within the framework of their research results:

a reduction in the vibration and noise emissions for the switched reluctance machine

installation of a switched reluctance machine into a conventional E-vehicle, working as a wheel-hub powered drive

the design of a new type of control equipment for governing the electric power unit, and for enabling communication within the existing architecture of the vehicle electrical system

an integration of the vehicle-drive algorithms from the previous Research Project ‘E4x4’

a conversion of a serial Ford Focus Electric to use the ‘SR4Wheel’ drive

State Funding and Promotion

The idea for the ‘SR4Wheel’ Project was thus born, and initial trials for the feasibility and the financing have been completed. Project sketches have been produced and rejected, working plans and calculations have been undertaken and verified, again and again. A long drawn-out process for the state funding and the monetary proceeds has taken its course, and finally led to success after 14 months of intense preparations.

Within the scope of the research project competition of the ‘Leitmarkt Agentur.NRW’ of the German Federal State of North Rhine Westphalia, ‘SR4Wheel’ has finally received the recommendation of the Government of North Rhine Westphalia, and the state promotion and funding was subsequently awarded for proceeding with the project in April 2016.

‘SR4Wheel’ is thus one of the leading projects within the scope of research activities for alternative road vehicle drive concepts for electromobility in Germany.

At a glance

Project Name:SR4WheelSwitchedReluctance4–Wheel-Drive

Project Goal:Research and Realization of a Wheel- Hub and Rim -Drive as a gearless-head reluctance stepper motor drive unit

State Funding Providers:Leitmarkt Agentur.NRW (Agency of the German Federal State of North Rhine Westphalia), Mobilitaet & Logistik.NRW (Agency of the German Federal State of North Rhine Westphalia), Germany